A comparison between predicted and measured sea echo Doppler spectra for surface wave radar

Development of the Surface Wave Radar test bed at Cape Bonavista, Newfoundland was initiated in 1985. The facility has been used to investigate all aspects of surface wave radar and to provide data for evaluating and developing models of radar performance. Trials have been conducted at the site that demonstrate beyond-the-horizon detection of aircraft to 300 km, surface targets to 500 km, and icebergs to 300 km. The need to predict surface wave radar performance under differing tasks, system parameters and environmental conditions has led to the development of a generalized computer simulation package. An integral part of the development has been the testing and progressive refinement of different components of the simulation package based on experimental results and other advances. The simulation software includes modules that provide estimates of transmission loss, sea clutter, and external noise levels. Of interest in this paper are the sea clutter models and in particular two additional scattering features that are predicted and have been observed to occur outside of the Bragg resonant region. The first of these additional scattering features is referred to as 'off resonance first order clutter' whilst the second is referred to as 'the second-part of second order clutter'. This latter clutter has been predicted to occur when scattering from the ocean occurs from both behind and in front of the transmit point. The scattering mechanism can be visualized as being similar to a repeated first order scatter. Results are presented that illustrate the effect of this scattering mechanism and how it influences the ocean spectrum for surface wave radar.<>